<template>
    <div class="todo-footer"  v-show="total">
      <label>
        <input type="checkbox" :checked="isAll" @change="checkAll"/>
      </label>
      <span>
        <span>已完成{{ doneTotal }}</span> / 全部{{ total }}
      </span>
      <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
    </div>
  </template>
  
  <script>
  export default {
    name: 'MyFooter',
    props:['todos','checkAllTodo','clearAllTodo'],
    computed:{
      isAll(){
        return this.total===this.doneTotal && this.total>0
      },
      total(){
        return this.todos.length
      },
      doneTotal(){
         return this.todos.reduce((pre,todo)=>pre+(todo.done?1:0),0)
      }
    },
    methods:{
      checkAll(e){
        this.checkAllTodo(e.target.checked)
      },
      clearAll(){
        this.clearAllTodo()
      }
    }
  }
  </script>
  
  <style scoped>
  /*footer*/
  .todo-footer {
    height: 40px;
    line-height: 40px;
    padding-left: 6px;
    margin-top: 5px;  
  }
  .todo-footer label {
    display: inline-block;
    margin-right: 20px;
    cursor: pointer;
  }
  .todo-footer label input {
    position: relative;
    top: -1px;
    vertical-align: middle;
    margin-right: 5px;
  }
  .todo-footer button {
    float: right;
    margin-top: 5px;
  }
  </style>